Foldable back rest



FIG. 1 is a front elevational view of the foldable back rest in use position showing my new design;

FIG. 2 is a back elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a foldable back rest, as shown. 